Vehicles may include cooling systems configured to reduce overheating of an engine by transferring the heat to ambient air. Therein, coolant is circulated through the engine block to remove heat from the hot engine, and the heated coolant is then circulated through a radiator near the front of the vehicle. Heated coolant may also be circulated through a heat exchanger to heat a passenger compartment. The cooling system may include various components such as various valves and one or more thermostats.
While vehicles may include cooling systems to reduce overheating of the engine, it may additionally be understood that vehicle systems tend to operate most efficiently when in an optimal temperature range. For example, operating the engine well above the optimal temperature may present durability complications, while operating the engine well below the optimal temperature may result in degraded efficiency. Thus, opportunities exist to increase efficiency by helping engine systems reach and maintain their optimum operating temperature rapidly during a cold start.
Toward this end, US Patent Application US 2013/0255604 teaches a cooling system configured to circulate coolant to various vehicle system components via a plurality of valves. Such valves may include a bypass shut-off valve, a heater shut-off valve, a thermostat valve, a transmission cooling valve, a transmission heating valve, etc. During an engine cold start, the heater shut-off valve and the bypass shut-off valve may be closed for a first duration to stagnate coolant at the engine and expedite engine warm-up. Then, after the engine has been sufficiently warmed, one or more of the bypass shut-off valve and the heater shut-off valve may be actuated open to allow the previously stagnating, and now heated, coolant to reach the thermostat. Responsive to the heated coolant reaching the thermostat, the thermostat valve may be opened, resulting in coolant flow through a radiator.
However, the inventors herein have recognized potential issues with such an approach. First, stagnating coolant flow in the engine to allow for rapid warm-up may result in durability issues, due to uneven heating of various engine components. Furthermore, the use of electronic valves to selectively control coolant circulation in various coolant loops is costly, and adds complexity to the vehicle system. For example, the addition of costly electronic valves necessitates the continual diagnosis of the valves, to ensure the valves, and thereby the vehicle cooling system, is functioning as desired.
The inventors herein have recognized these issues, and have developed systems and methods to at least partially address the above issues. In one example, a method is provided, comprising during an engine startup event, controlling a flowpath of an engine coolant in a vehicle cooling system via a passive valve and an actively regulatable valve; and responsive to an engine coolant temperature below a threshold at the engine startup event, isolating the flowpath of engine coolant to a subsection of the cooling system to enable rapid warming of the engine coolant without stagnating the engine coolant at an engine.
In one example, controlling the flowpath of the engine coolant in the vehicle cooling system via the passive valve comprises controlling the flowpath of the engine coolant in the vehicle cooling system via a first thermostat valve of a first thermostat positioned on a hot-side of the engine, including controlling the first thermostat valve to a first, a second, or a third position based on engine coolant temperature as sensed by a first temperature sensing element of the first thermostat, without input from a vehicle controller. In such an example, controlling the flowpath of the engine coolant in the vehicle cooling system via the actively regulatable valve comprises controlling the flowpath of the engine coolant in the vehicle cooling system via a second thermostat valve of a second thermostat positioned on a cold-side of the engine, including one or more of controlling the second thermostat valve to a fourth, a fifth, or a sixth position based on engine coolant temperature as sensed by a second temperature sensing element of the second thermostat without input from the vehicle controller; and controlling the second thermostat valve to the fifth or sixth position actively by activating an electric heater associated with the second thermostat thereby raising a temperature of the second thermostat.
In another example, controlling the flowpath of the engine coolant in the vehicle cooling system via the passive valve comprises controlling the flowpath of the engine coolant in the vehicle cooling system via a third thermostat valve of a third thermostat positioned on a cold-side of the engine, including controlling the third thermostat valve to a seventh, an eighth, or a ninth positon based on engine coolant temperature as sensed by a third temperature sensing element of the third thermostat, without input from a vehicle controller. In such an example, controlling the flowpath of the engine coolant in the vehicle cooling system via the actively regulatable valve comprises controlling the flowpath of the engine coolant in the vehicle cooling system via an actuatable solenoid valve positioned on the cold-side of the engine, and where the actuatable solenoid valve is configurable in an open position, or a closed position.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.